The present application relates to an optical recording medium, such as an optical disc, and in particular, to a recording layer material thereof.
In recent years, the recording density and the capacity of optical discs, which is one of the media using an optical information recording method, have improved along with the spread of personal computers, the start and spread of terrestrial digital broadcasting, and the spread of high-definition televisions to homes. For example, a CD (Compact Disc) and a DVD (Digital Versatile Disc), a Blu-ray disc (registered trademark), and an optical disc recording medium capable of recording a larger amount of information are available.
The Blu-ray disc, as a large-capacity optical disc recording medium, is an optical disc which has a diameter of about 12 cm and a thickness of about 1.2 mm. As its layer structure in the thickness direction, an information recording layer is formed in an uneven shape on a substrate with a thickness of about 1.1 mm. The information recording layer is formed by sequentially laminating a reflective film (metal thin film), a dielectric film, a recording film, and a dielectric film, for example.
In addition, a light transmissive layer (cover layer) with a thickness of about 0.1 mm is formed on the information recording layer.
Such a Blu-ray disc has a storage capacity of about 25 GB (Giga Byte).
Regarding a recording material for the recording film, for example, materials disclosed in JP-A-2008-112556 are known.